{  11 February 2011. Individual Olympiad. Problem set: http://neerc.ifmo.ru/school/io/archive/20110211/problems-20110211-individual.pdf
	Problem A
	Points: 100
}
uses SysUtils;
var s,res:string; t:set of char; i:integer;
begin
reset(input,'suffix.in');
rewrite(output,'suffix.out');
readln(s);
t:=[];
res:='';
for i:=1 to length(s) do begin
  if not(s[i] in t) then begin
    res:=res+s[i];
    t:=t+[s[i]];
  end;
end;
writeln(res);
end.
